Track support for pallet carrier



Nov. 9, 1965 J. E. BLONSKY 3,216,520

TRACK SUPPORT FOR PALLET CARRIER Filed July 3, 1963 5 Sheets-Sheet 1 INVENTOR Joseph E Blonsky BUM f. vZ/

AGE/VT Nov. 9, 1965 J. E. BLONSKY 3,216,520

TRACK SUPPORT FOR PALLET CARRIER Filed July 3, 1965 5 Sheets-Sheet 2 INVENTOR Joseph E. B/onsky AGE/VT Nov. 9, 1965 J. E. BLONSKY TRACK SUPPORT FOR PALLET CARRIER 5 Sheets-Sheet 3 Filed July 3, 1963 IHI|-I \vuwN/a m.

AGE/VT 1965 J. E. BLONSKY TRACK SUPPORT FOR PALLET CARRIER 5 Sheets-Sheet 4 Filed July 3, 1963 I N VEN TO R Joseph E. B/ons/ry AGENT Nov. 9, 1965 J. E. BLONSKY TRACK SUPPORT FOR PALLET CARRIER 5 Sheets-Sheet 5 Filed July 3, 1963 INVENTOR. Joseph E. Blonsky 3,216,520 TRACK SUPPORT FOR PALLET CARRIER Joseph E. Blonsky, Summerville, S.C., assiguor to West Virginia Pulp and Paper Company, New York, N.Y., a corporation of Delaware Filed July 3, 1963, Ser. No. 292,807 4 Claims. (Cl. 1899.24)

This invention relates to self-powered devices for handling materials and particularly relates to motorized vehicles for transporting bulky and heavy materials over difficult terrain. The invention specifically pertains to tracked, motorized, self-loading, pulpwood-transportin-g vehicles designed for close-quarter work in removing pulpwood from dense timber stands.

The consumption of pulpwood during 1961 in the United States Was in excess of 42 million cords, according to Pulp & Paper1962/World Review, page 122. A significant portion came from lumber and veneer residuals (for instance, about 26% of the 33,263,000 cords of coniferous pulpwood used last year came from residual chips), but most had to be extracted from the forests as relatively small logs of pulpwood length.

In the manufacture of paper and linerboard from pulpwood, the cost of the pulpwood is an important economic factor. Moreover, the costs of converting pulpwood from standing timber to roundwood logs delivered to a railhead are a very significant part of the total cost and can be even larger than the cost of converting the logs to slush pulp ready for papermaking. For example, at a large kraft papermill in the southeastern United States, the avenage costs on an equivalent basis for cutting down pine trees, bucking the trees into pulpwood logs, making up the logs into pallets, and delivering the filled pallets to a railhead were in 1962 about 22% greater than the cost of converting the logs into pulp ready for papermaking.

Because wood costs are a large item in pulp manufacture, it is highly important that maximum efficiencies be attained in Wood procurement. At present, the operation of harvesting pu-lpwood from the forests and transporting the log lengths from the stump sites to roadside pickup locations is unduly demanding of equipment capacities and of labor and is consequently excessively costly.

Certain forestry practices used in modern forest management are excellent from the standpoints of efiiciency, fire protection, and production volume, but they create particular problems in Wood procurement. Examples are thinning out dense stands of young trees and removing top remnants of fallen trees after harvesting large trees for poles, piling, and raw timber. Using conventional skidding methods, it is very diflicult to assemble payloads under these conditions, even though the terrain is favorable. To decrease costs by simplifying operations, it is desirable to devise novel methods and equipment, particularly because economic conditions and world-wide growth in wood usage indicate that intensive forest management is certain to increase.

Currently used methods for moving pulpwood from a cutting site, Where the terrain may be hilly, swampy, overgrown with underbrush, rocky, or excessively dense in standing trees, include tree length skidding and handling of cut pulpwood logs as palletized loads. Palletizing requires the cutting of trees into desired log lengths (5 feet in the southeastern United States) 'and horizontally stacking these short logs within suitable metal frames called pallets, such as are described in co-pending application No. 197,450, which act as bins and hold 1 /2 to 1 /51 cord-s. A typical pallet when loaded with hardwoods weighs about 6,100 pounds and when loaded with softwood weighs about 5,500 pounds. These filled pallets may then be handled as units by such methods as panning (towing a pallet on a metal tobaggan) or load- States Patent 0 ing one or more filled pallets aboard tractor-drawn trailers for towing to a roadside location Where fast fourpal'let trucks can conveniently pick up the pallets and rapidly transport them to a paper mill.

The general object of the instant invention is to provide a self-powered mobile device of exceptional compactness and stability that is capable of self-loading, transporting, and self-unloading of heavy objects without need for auxiliary vehicles over difficult terrain.

It is a particular object of the instant invention to provide a motorized vehicle which can perform tree-length skidding and can also transport heavy pallets filled with pulpwood from stump sites to roadside locations over unstable soil, through heavy underbrush, or over difi'icult terrain in addition to self-loading and self-unloading of these pallets.

It has been found that the best design to accomplish this objective is a tracked vehicle having its power plant and operator station in cantilevered relation to the body of the vehicle and its ground-contacting means. This invention is essentially based upon the concept that a very heavy and awkward load may be most efiiciently transported if placed as near to the ground and as directly centered above the ground-engaging means as possible; in accordance with this concept, the engine and operator station, having comparatively little Weight, are most advantageously displaced horizontally in order to prevent interference with the payload, to furnish maximum operator visibility, and to permit ready access to the engine.

As designed, the compact, versatile, powered vehicle of this invention has a short turning radius, great traction power, and high maneuverability over broken ground; most importantly, this vehicle has ideal load-distribution characteristics for high-capacity transportation of heavy and bulky materials over difiicult terrain. Accordingly, the self-powered vehicle of this invention, when suitably modified and when traveling either on a multiplicity of wheels or on endless tracks, has potential utility for a wide variety of agricultural, mining, and industrial purposes, as, for example, self-propelled tote boxes, scrap rnjetal transportation vehicles, short-distance ore carriers, oil-field drilling trucks, and prime movers for land preparation; in addition, a vehicle having these characteristics is readily adaptable to military operations as a weapons carrier or ammunition truck.

The particular object for this invention is acccomplished by means of a tracked skidder and pallet carrier having a cantilevered power plant and operator station, as shown in the drawings, which is eminently suitable for treelength skidding and for on-deck transportation of loaded pallets. Because of its low deck level, it is also very satisfactory for sequential loading of five-foot logs at a succession of stump sites. Various embodiments of this P powered vehicle, illustrating a basic structural design and Varied arrangements of parts, are shown in the drawings and described in the specification and claims.

In the drawings:

FIGURE 1 is a side view of a tracked embodiment of the invention which has a tiltable bed and tandem arrangement of engine and driver station, both supported by a cantilever attached to the vehicle frame.

FIGURE 2 is a top view of the structure shown in FIGURE 1.

FIGURE 3 is a side view of another embodiment of the invention which shows a side-by-side arrangement of engine and driver station with the engine being connected to the differential by means of a generally vertical driveshaft.

FIGURE 4 is a top view of the embodiment shown in FIGURE 3.

FIGURE 5 is a side view of the side-by-sicle embodiment of FIGURES 3 and 4 which shows another method of compacting the engine and frame by means of a rearward-mounted power transfer box or gearbox.

FIGURE 6 is a top view of the structure shown in FIG- URE 5.

FIGURE 7 is an enlarged partial fore-and-aft section of the tandemly-arranged embodiment from FIGURE 2, as indicated at 7-7 therein.

FIGURE 8 is an enlarged transverse section from FIG- URE 1, as indicated at 88 therein.

FIGURE 9 is an enlarged perspective view of the bogie frame brackets showing the bogie gussets and locking blocks.

FIGURE 10 is a horizontal sectional view taken approximately through the middle of the bracket 28.

Referring to the drawings, these embodiments of the invention are vehicles comprising a vehicle frame which is available in its entirety for load supporting, a ground-engaging propelling means, and a power-and-operator section which is cantilevered from the vehicle frame at one end thereof and which contains the power generating means and the operator station. The power generating means may be any suitable source of power such as an internal combustion engine or an electric motor. The vehicles shown in the drawings are powered with a Ford tractor engine of in-line design or with a diesel engine of equivalent horse power, but a shortened V-6 engine or a radial piston engine could be used to decrease engine overhang.

"The operator station may be in tandem relation to the engine or in side-by-side relation thereto, as illustrated in FIGURES 2, 4, and 6. The operator station generally has a seat and vehicular instruments and controls.

The vehicles of this invention are built around a very rigid and strong main frame 14. Rotatably attached to the main frame on each side of a vehicle are rotatable track assemblies supporting the weight of the vehicle and its load. These assemblies include well known suspension systems in the vehicular art called bogies which have been widely used for military half-track vehicles, as shown by Knox in US. 2,093,456. These bogies have fiat spiral springs built into their structure to absorb the weight of heavy loads and the shocks caused by movement over uneven terrain.

Comprising each rotatable track assembly are an endless track 21, the sprocket driving wheel 22 with inner and outer flanges, the split-flanged idler wheel 23, and the bogie cluster assembly which is comprised of a bogie frame bracket 28, volute springs within the frame bracket which are not visible in the drawings, a crab 61, bogie rollers 25, bogie frames 26, and bogie arms 27. The tracks 21 encircle the pairs of bogie rollers 25 as well as the driving and idler wheels 22, 23 on each side of the vehicle and are releasably engaged by projecting tabs or sprocket teeth on the sprocket wheels 22 and idler wheels 23.

The idler wheels 23 at the rear of a vehicle of this invention are attached to the main frame 14 by means of idler shackles 24 mounted with spring-loaded track-tightening arms 57 to maintain proper tension on the tracks 21. The tracks 21 are an endless-band type made of rubber moulded to steel cables which extend longitudinally the length of the tracks. Metal guide plates with steel cross members are bolted to the cables along the inside center of each track. These plates serve as contacts for the sprocket teeth on the sprocket driving wheels 22 and idler wheels 23 and also function as guides to keep the tracks 21 aligned and in contact with the bogie rollers 25. The edges of the tracks also have metal tabs which protect outwardly to give added traction.

' The bogie rollers 25 are steel wheels with solid rubber tires which have a deep center groove within which the guide plates, on the inside of each revolving endless rub ber track 21, mesh. The rollers 25, riding upon the tracks 21, resiliently bear the load and press down on the rubber tracks 21 to follow the contour of the terrain.

The bogie frame brackets 28 are connected to each other by a tubular bogie axle 51 and are rigidly attached, as by welding, to the main frame 14. Inside each bracket 28 are dual volute springs, which are not visible in the drawings, resting upon the upper surface of a crab 61 which is movably confined by the downwardly projecting sides 60 of the bracket 28 so that the crab 61 can freely move up and down within the confines of the bracket 28 and pivot with relatively little restriction. Each crab 61 is an H-shaped member in recumbent position having a crossbar of nearly the same length as the inside width of bracket 28 and four horizontally extending legs 29 extending beyond the downwardly projecting sides 60 of the brackets 28 approximately parallel with the tracks 21 while straddling the rollers 25. It is upon the relatively wide crossbar of each H-shaped crab 61 that the dual volute springs rest inside the bracket 28. Each leg 29 of a crab 61 rests upon the middle of a bogie arm 27, as shown in the drawings, which is hingeably attached to a downwardly-projecting side 60 of the bracket 28 at one end and at the other end to the center of a bogie frame 26 which is itself rotatably attached at each end to the shafts of a pair of bogie rollers 25. The frame brackets, crabs, volute springs, bogie arms, bogie frames, and bogie rollers are clearly shown in FIGURES 9, l0, and 11 of US. 2,093,456 by Knox.

For hard usage over difficult terrain, additional strengthening of the front end of this bogie system is needed. Bogie gussets 58, in front of each side of each bracket 28, restrict upward movement of the front pairs of bogie arms 27. Bogie locking blocks 59, above each frame 26 on each side of the front pairs of bogie rollers as shown in the drawings, restrict upward movement of the front rollers 25. If the tracks 21 are lengthened and an extra bogie roller is added to each side of the bogie assembly, however, the supporting members 58 and 59 may be omitted, and forward shock-absorbing springs may be added between the main frame 14 and the four bogie frames 26.

Rigidly attached to the main frame 14 at the front of the vehicle are very rigid and strong members, which may also be of six-inch ship-building channel iron, and which function as cantilevers in supporting the power source and the operator station. These members comprise the engine frame 13. A cantilever is herein defined as a beam or truss supported at one end only, or a section of a beam or truss overhanging a support, using the definition given on page 439, volume 2, of the McGraw Hill Encyclopedia of Science and Technology, 1960.

A typical power source is an internal combustion gasoline or diesel engine 30. The engine 30 is supported by and rigidly attached to the engine frame 13. Also rigidly attached to the engine frame 13 are the belly pan and motor base 12, the operator platform 16, the brush deflector 15, and the head rack 11. The operator station is located on the operator platform 16 and is generally equipped, as vehicular control instruments, with a brake pedal, a clutch pedal, steering levers 54, an operator seat 55, and an instrument console 56, in any suitable arrangement. The engine 30 and the operator station are in tandem relation in the embodiment shown in FIGURES 1 and 2; in FIGURES 3, 4, 5, and 6 they are in side-byside relation. This arrangement with customary seat design aifors excellent operator visibility except on the right side, but the operator seat 55 can easily be raised suffi ciently to enable the operator to see directly over the engine 30.

Furthermore, for difficult maneuvering in close quarters particularly on other embodiments than those illustrated in the drawings, the operator seat 55 can be supported on a hydraulic-powered column and swivelled around at any reasonable height while maintaining con- 2) trol of the vehicle by means of suitable remote-controlling means.

For the embodiments illustrated in the drawings, it is simply sufficient to provide remote-controlling means so that the operator may operate the vehicle while standing up and facing to the rear as is often useful during loading and unloading of pallets.

In the instant embodiments, the engine 30 transmits its power to the drive wheels 22 through a transmission 31, a clutch, a differential pinion shaft 32, and a differential 34, as shown in FIGURES 1 and 2. The transmission gear box in the transmission 31 has four forward speeds and one speed in reverse. A suitable differential ratio is 7:1. The compact design shown in FIGURES 3 and 4 utilizes an inverted angle head drive 33 to connect the elevated engine 30 downwardly, from a transmission 31 equipped with a downward bevel gear, to the differential 34 which has been rotated upwardly. The compact embodiment shown in FIGURES and 6 utilizes a primary driveshaft 37, a rearwardly mounted gearbox 39, a secondary driveshaft 38, and four universal joints 36 in connecting these members to the rearwardly aligned differential 34. However, a flexible coupling can be installed between the differential 34 and gearbox 39 as is used in the embodiment shown in FIGURES 1 and 2 gearbox 39 is a transfer case, having one input and three outputs. The radiator and fan may also be mounted horizontally above the engine, blowing air downward, to decrease engine overhang whereby vehicle stability and close-quarter maneuverability are improved. Alternatively, the radiator may be hingeably mounted alongside the engine on the right-hand side. An aluminum engine may be installed to decrease front-end weight.

To keep costs low, the embodiments of the invention herein described utilize conventional differential axes of the automotive type as friction drives through brake drum-an-shoe contacts 61. Left-hand and right-hand steering lever 54 work through independent, automotivetype, master hydraulic cylinders to apply braking forces to one of the tracks 21, whereby the vehicle is turned as gradually as desired. Replacements of the brakes, drums, and shoes are inexpensive, and the parts are easily accessible. However, other methods of transferring power to the tracks 21 and other steering means may be utilized as desired. For instance, hydraulic transmission of power to hydraulic motors at each wheel can be used. Moreover, the concept herein disclosed may be successfully embodied in a vehicle having a multiphcity of wheels instead of endless tracks.

Hingeably attached to the main frame 14 at bed hinge 44 is the bed 40 which is comprised of the flared tail 46, bed rails 42, transverse box member 47, and counterweight 41. The hinged bed 40 may be tiltably raised and lowered, preferably by a double-acting hydraulic piston 49 which is pivotably attached to the bogie axle 51, as shown in the drawings. The fuel tank, not shown in the drawings, may also be located beneath the flared tall 46 to help counterbalance the power and operator section.

The tail 46 may also be foldably hinged, at any position rearward of the bed hinge 44, to permit upward folding of the tail 46. With this tail 46 in vertical position after on-loading of a filled pallet, longitudinal staybars, which can be hingeably attached to the bed 40, can be moved into locking position with the tail 46. Alternatively, a heavy chain can be used to hold the tail 46 in position. These arrangements constitute another means of safely retaining a heavy pallet on the bed 40.

Another useful modification of the tracked skidder and pallet carrier of this invention is to increase the slope from front to rear of the bed 40, thereby facilitating the loading and unloading of pallets. Moreover, the bed may be attached to the main frame 14 at a suficiently steep angle to permit a loaded pallet 20 to be pulled by the cable 50 up on individually hinged loading tracks, which are selectively attached to the tail 46 but are not shown in the drawings, if the tail 46 is appreciably shortened. The pallet 20 can then be partially suspended from the cable 50 while resting on the bed 40. The increased slope of the fixed bed 40 is suiiicient, when the cable 50 is released, to cause the pallet 20 to slide down the bed 40 and down the hinged loading tracks into contact with the ground, particularly if small rollers are rotatably inserted into the bed rails 42 and into the hinged loading tracks. Consequently, the bed 40 can be fixed instead of tiltable. Hinging .of the tail 46 or of the hinged loading tracks to permit only upward folding thereof is particularly advantageous, however, with a steeply sloping bed to provide a safety device if the cable 50 slips and to minimize contact with the ground.

To pull empty or loaded pallets onto the vehicle of this invention, a powered winch is useful. In the instant embodiment, the forward-and-reversing worm gear winch 45 is mounted slightly below the level of the tiltable bed 40 and slightly forward of the bed hinge 44. The winch 45 is chain-reaction driven at 500 rpm. from a splined power take-off at the transmission 31 which is connected to the power take-off shaft and gear 19. The cable 50 passes forwardly from the winch 45 to and over the sheave 43 and rearwardly to the pallet to be loaded thereupon. The pulling force may thus be represented as a vector that is essentially parallel to the bed 40 when this bed 49 is tilted toward the ground.

For tree-length and log skidding and for panning operations, it is desirable to use a higher pulling position. A detachable A-frame, which is not shown in the drawings, having a roller mounted thereon may be bolted onto the vehicle above the front end of the frame 14. The cable 50 can then be passed over this roller to the tow. An alternative method is to strengthen the head rack 11 and to mount a roller thereupon at position 18 as shown in FIGURES 3 and 5. Still another alternative is to mount a roller in the upwardly folded and locked tail 46. The cable 50 can then pass directly from the Winch 45 to the roller and thence to the load or from the Winch 45 to the sheave 43 to the roller. If the bed 40 is fixed at an increased slope, it is feasible to mount the winch 45 near the transmission 31 or even at the head of the bed 40 in place of the sheave 43.

All of the tracked embodiments shown in FIGURES 1-6 operate on a pushing principle, with reference to the tracks; alternatively, it may be said that tracked vehicles having the driving wheels in front pull the tracks from the rear. By connecting a primary driveshaft 37 directly to a differential 34 on the rear axle, the present idler wheels 23 can become driving wheels, and the tracks 21 can be pulled directly. The principal objection thereto is the very small distance between the ground and the bottom of the differential 34 which then exists. This modification is most useful if the tracks 21 are lengthened and another bogie wheel 25 or set of bogie wheels 25 is added on each side while the angle of attachment of the main frame 14 to the bogie frame brackets 28 is altered to make the main frame 14 more nearly parallel with the ground and to elevate the existing idler wheels 23 above the ground. This arrangement also facilitates movement of the vehicles in reverse over uneven ground.

A mechanical loader, operated with the cable 50 from the winch 45, can conveniently be installed on the skidder and pallet carrier of this invention, as on the left front portion of the vehicle, for example. For the embodiments shown in FIGURES 36, the loader is preferably installed behind the operator seat 55. The preferred mechanical loader is hinged at about the height of the head rack 11 so that the upper portion folds over and rests thereupon or is aligned therebehind when not being used for loading pulpwood. To surmount a pallet which is six feet long and seven feet high, the total height of the loaded post above the bed 40 must be at least 8 /2 feet. An attached boom of manual swing-out design, having a five-foot length, constructed of aluminum and having a capacity of at least one thousand pounds, can be controlled by the operator when standing up and facing to the rear, while handling the vehicle with remote-controlling means, to load pulpwood into a pallet 20. This mechanical loader can be very helpful with heavy hardwood logs.

In operation, the mobile, tracked skidder and pallet carrier embodying the principles of this invention carriers one to two empty pallets 20 to a cutting site or deck and either winches a filled pallet onto the tilted bed 40 or stands by at the stump site while cut pulpwood is loaded into a pallet 20 which is centered on the bed 40 or which may be towed behind the empty vehicle and winched thereupon when filled. If a sufficient supply of cut logs is not available at one site, the tracked vehicle can be moved at will to another site at speeds up to 35 miles per hour. With a full pallet aboard, the vehicle can proceed cross-country to a roadside pickup location to unload the full pallet and pick up an empty pallet. Unloading is done preferably by means of the double-acting hydraulic piston 49 to tilt the bed 40 and cause the filled pallet 20 to slide downward under control of the winch 45 and cable 50. However, if the bed 40 has been fixed at an increased slope, instead of being tiltable, the filled pallet 20 may be slid down the bed 40 and down the hinged loading tracks onto the ground.

As a carrier of weapons and ammunition, the mobile vehicle of this invention has outstanding qualities of visibility and maneuverability, particularly with a side-byside cabin design, for a single operator. Maximum loading space is available directly above the ground-contacting means, and maximum stability may be thereby achieved by centering very heavy loads thereupon. The cab can be armored and an air-cooled engine can be installed for maximum invulnerability to enemy fire;

I claim:

1. In a motorized vehicle having:

(a) a main frame having a front end and a rear end,

(b) a load-supporting bed which is directly above the main frame and attached thereto,

() a cantilevered front section, attached to said main frame at the front end, which supports an operator station and a power-generating means, and

(d) rotatable track assemblies, for supporting and propelling the motorized vehicle, which are attached to the main frame on each side thereof and are connected to the power-generating means, each assembly comprising: Y

(1) a sprocket driving wheel which is rotatably attached to the main frame near the front end and which is connected through power-transmitting means to the power-generating means,

(2) an idler wheel which is rotatably attached to the main frame near the rear end by means of a spring-loaded track-tightening arm,

(3) an endless track which encircles and engages the sprocket driving wheel and the idler wheel, receiving power from the sprocket driving wheels and contacting the ground on its lower run between said wheels, and

(4) a bogie cluster assembly comprising:

(a) bogie rollers, having axial shafts, which ride upon the track on its lower run between said wheels in forward and rearward pairs,

(b) bogie frames, linking together the rollers of each roller pair on each side thereof, which are rotatably attached at each end to said axial shafts,

(c) a bogie frame bracket which is rigidly attached to the main frame at a selected angle thereto, (cl) a crab, mounted with bogie frame bracket, which has four legs extending in forward and rearward pairs approximately parallel with the tracks and astraddle of the rollers,

(e) dual volute springs, mounted within the bogie frame bracket, which rest upon the crab, and

(f) bogie arms which are pivotally attached to the frame bracket at one end and which are pivotally attached at the other end to the bogie frames between the rollers of each pair of bogie rollers and on each side thereof,

the improvement in the front end of each rotatable track assembly, which comprises:

(a) rigid bogie gussets, located above the forward pair of legs of the crab and rigidly attached to the front edges of the bogie frame bracket, which restrict upward movements of the forward pair of legs of the crab and of the front pair of bogie arms, and

(b) rigid bogie locking blocks, attached to each bogie arm and extending horizontally forward above each bogie frame, which restrict upward movement of the front roller of the forward pair of bogie r-ollers,

whereby the forward longitudinal pivot of said motorized vehicle is maintained at the front bogie roller.

2. The motorized vehicle of claim 1 wherein:

(a) the power-generating means is an engine which is rigidly attached to and supported by the cantilevered front section, and

(b) the power-transmitting means comprises a driveshaft which is connected to the engine, a transmission and clutch which are connected to the driveshaft, a differential pinion shaft which is connected at each end to the sprocket driving wheels, and a differential which is mounted on the differential pinion shaft and is connected to the transmission.

and clutch.

3. The motorized vehicle of claim 2 wherein the engine is elevated and is connected by means of an inverted angle head drive to the transmission which is equipped with a downward bevel gear and is connected to the upwardly rotated differential.

4. The vehicle of claim 2 wherein the transmission is connected to the differential by the sequential arrangement of a primary driveshaft, a rear-mounted gearbox, and a secondary driveshaft which is aligned at an acute angle to the primary driveshaft.

References Cited by the Examiner UNITED STATES PATENTS ARTHUR L. LA POINT, Primary Examiner, 

1. IN A MOTORIZED VEHICLE HAVING: (A) A MAIN FRAME HAVING A FRONT END AND A REAR END, (B) A LOAD-SUPPORTING BED WHICH ISDIRECTLY ABOVE THE MAIN FRAME AND ATTACHED THERETO, (C) A CANTILEVERED FRONT SECTION, ATTACHED TO SAID MAIN FRAME AT THE FRONT END, WHICH SUPPORTS AN OPERATOR STATION AND A POWER-GENERATING MEANS, AND (D) ROTATABLE TRACK ASSEMBLIES, FOR SUPPORTING AND PROPELLING THE MOTORIZED VEHICLE, WHICH ARE ATTACHED TO THE MAIN FRAME ON EACH SIDE THEREOF AND ARE CONNECTED TO THE POWER-GENERATING MEANS, EACH ASSEMBLY COMPRISING: (1) A SPROCKET DRIVING WHEEL WHICH IS ROTATABLY ATTACHED TO THE MAIN FRAME NEAR THE FRONT END AND WHICH IS CONNECTED THROUGH POWER-TRANSMITTING MEANS TO THE POWER-GENERATING MEANS, (2) AN IDLER WHEEL WHICH IS ROTATABLY ATTACHED TO THE MAIN FRAME NEAR THE REAR END BY MEANS OF A SPRING-LOADED TRACK-TIGHTENING ARM, (3) AN ENDLESS TRACK WHICH ENCIRCLES AND ENGAGES THE SPROCKET DRIVING WHEEL AND THE IDLER WHEEL, RECEIVING POWER FROM THE SPROCJET DRIVING WHEELS AND CONTACTING THE GROUND ON ITS LOWER RUN BETWEEN SAID WHEELS, SAID (4) A BOGIE CLUSTER ASSEMBLY COMPRISING: (A) A BOGIE ROLLERS, HAVING AXIAL SHAFTS, WHICH RIDE UPON THE TRACK ON ITS LOWSER RUN BETWEEN SAID WHEELS IN FORWARD AND REARWARD PAIRS, (B) BOGIE FRAMES, LINKING TOGETHER THE ROLLERS OF EACH ROLLER PAIR ON EACH SIDE THEREOF, WHICH ARE ROTATABLY ATTACHED AT EACH END TO SAID AXIAL SHAFTS, (C) A BOGIE FRAME BRACKET WHICH IS RIGIDLY ATTACHED TO THE MAIN FRAME AT A SELECTED AWNGLE THERETO, (D) A CRAB, MOUNTED WITH BOGIE FRAME BRACKET, WHICH HAS FOUR LEGS EXTENDING IN FORWARD AND REARWARD PAIRS APPROXIMATELY PARALLEL WITH THE TRACKS AND ASTRADDLE OF THE ROLLERS, (E) DUAL VOLUTE SPRINGS, MOUNTED WITHIN THE BOGIE FRAME BRACKET, WHICH REST UPON THE CRAB, AND (F) BOGIE ARMS WHICH ARE PIVOTALLY ATTACHED TO THE FRAME BRACKEWT AT ONE END AND WHICH ARE PIVOTALLY ATTACHED AT THE OTHER END TO THE BOGIE FRAMES BETWEEN THE ROLLERS OF EACH PAIR OF BOGIE ROLERS AND ON EACH SIDE THEREOF, THE IMPROVEMENT IN THE FRONT END OF EACH ROTATABLE TRACK ASSEMBLY, WHICH COMPRISES: (A) RIGID BOGIE GUSSETS, LOCATED ABOVE THE FORWARD PAIR OF LEGS OF THE CRAB AND RIGIDLY ATTACHED TO THE FRONT EDGES OF THE BOGIE FRAME BRACKET, WHICH RESTRICT UPWARD MOVEMENTS OF THE FORWARD PAIR OF LEGS OF THE CRAB AND OF THE FRONT PAIR OF BOGIE ARMS, AND (B) RIGID BOGIE LOCKING BLOCKS, ATTACHED TO EACH BOGIE ARM AND EXTENDING HORIZONTALLY FORWARD ABOVE EACH BOGIE FRAME, WHICH RESTRICT UPWARD MOVEMENT OF THE FRONT ROLLER OF THE FORWARD PAIR OF BOGIE ROLLERS, WHEREBY THE FORWARD LONGITUDINAL PIVOT OF SAID MOTORIZED VEHICLE IS MAINTAINED AT THE FRONT BOGIE ROLLER. 